The invention relates to a revolving door for the protection of the access to and/or exit from a room, comprising a revolving shaft with a number of door wings spaced evenly around it, a pair of panels at opposite ends bordering on the path followed by the door wings and forming a partly closed zone with a first and a second opening, a drive motor for the shaft and a control unit for the drive motor, including a monitor unit with detection aerial, which aerial generates a detection field, such that when a person carrying an authorization card enters the detection field the monitor unit sends an enable signal to the control unit to turn the shaft through a predetermined angle in the direction of passage to allow the person concerned to proceed from the one opening to the other.
Such revolving doors are known in a number of different types and have the advantage that the person who wishes to pass the revolving door does not have to show his authorization card to a doorkeeper or insert it into a special card reader but, when approaching or entering the partly closed zone of the revolving door, the authorization card is detected by the detection field and the revolving door is activated automatically. A known revolving door of this kind has its detection aerial mounted to a windowpane in the one panel of the revolving door and a comparatively strong detection field has to be generated to make sure that the authorization card of the person entering the partly closed zone is detected. The known revolving door therefore has the disadvantage that the monitor unit, having detected an authorized person entering the partly closed zone of the revolving door through the first opening, again detects this person leaving this zone through the second opening, so that the control unit continues to activate the drive motor, making it possible for an unauthorized person to pass the revolving door. Because the detection field of the known revolving door extends beyond the revolving door itself, it is also possible that the monitor unit detects the authorization card of a person who in fact does not wish to pass the revolving door at all.
The object of the invention is to provide a revolving door of the type disclosed in the preamble, in which this disadvantage is effectively eliminated.